System to avoid icing in the discharge piping of a pressure relief valve

ABSTRACT

Apparatus for deicing the discharge gas from a safety relief valve includes a high pressure probe and an injection probe extending into the flow path of the discharge gas. Inlet orifices in the high pressure probe include inlet orifices facing directly upstream relative to the gas for communication of the total pressure of the flowing gas to the inside of a reservoir containing the deicing agent. The injection probe connects with an outlet of the reservoir and includes outlet orifices facing directly downstream of the discharge gas flow so that the reservoir is subjected to a driving pressure derived from the difference between the total pressure of the flowing gas and its reverse dynamic pressure. An adjustable connector mounting the high pressure probe in the discharge flow path of the gas allows the inlet orifices to be selectively oriented between positions facing directly upstream and perpendicular thereto to selectively vary the driving pressure.

This is a division of application U.S. Ser. No. 267,416 filed Nov. 4,1988, now abandoned.

TECHNICAL FIELD

This invention relates generally to pressure relief systems and, moreparticularly, to apparatus used to keep solids, such as ice, fromforming in the path of the discharge fluid from a pressure relief valveand inhibiting proper functioning of the relief valve.

BACKGROUND ART

In a pressure relief system, a substantial pressure reduction may beexperienced by the discharge fluid from a pressure relief valve when thefluid is vented from the system. As a result, the temperature of thisdischarge fluid may be lowered below the point at which variouscomponents of the discharge fluid may form into solids. If the solidsaccumulate to form a blockage in the discharge piping of the system, theblockage can increase the back pressure of the discharge fluid beingexhausted from the valve and thereby keep the relief valve fromfunctioning properly. To keep the solids from forming, prior systemshave used steam or electrical tracings to heat the discharge fluids fromthe relief valve so that the temperature of the discharge fluid is keptabove the temperature at which solids may form. Alternatively,anti-solidifying agents have been used to lower the temperature at whichsolids can form in the discharge fluid. For example, antifreeze has beeninjected into the discharge fluid to keep ice from forming. However,with respect to the use of anti-solidifying agents, in pressure reliefsystems designed for high pressure fluids such as process gases, themass flow of the gases discharged through the relief valve can requirethe anti-solidifying agent to be pumped into the stream of dischargegases at flow rates higher than that obtainable using a conventionalaspirator.

Examples of lower mass flow pressurized piping systems are air brakingsystems as are described in U.S. Pat. Nos. 1,171,014, 1,884,092 and1,220,336. The flow of fluid through the piping in these types ofsystems is used to draw antifreeze from a reservoir into the flowingfluid stream. These pressurized systems, however, handle only very smallmass flows at relatively low pressure conditions in comparison topressure relief systems.

For high pressure relief systems, some prior arrangements have usedsolenoid actuated pumping devices to inject the anti-solidifying agentinto the discharging gas. In the latter type of system, as with systemsutilizing steam or electrical tracings, energy is required from a sourceoutside the pressure relief system itself in order to inject theanti-solidifying agent.

DISCLOSURE OF INVENTION

The present invention aims to provide a new and improved arrangement forinjecting a sufficient quantity of an anti-solidifying agent into thedischarge fluid from a pressure relief valve to keep solids from formingin the fluid and to do so without having to rely on energy obtained froma source outside of the pressure relief system. A related object is toaccomplish the foregoing by utilizing an injection driving pressureobtained from the discharge fluid itself and, particularly a drivingpressure derived from the difference between the total pressure and thereverse dynamic pressure of the discharge fluid.

A more detailed object is to obtain a high pressure for injecting theanti-solidifying agent into the discharge fluid through use of high andlow pressure probes extending into the path of the discharge fluid.Specifically, the two probes communicate with a reservoir containing theanti-solidifying agent through inlet and outlet lines. The high pressureprobe includes an inlet orifice facing upstream of the discharge fluidflow so that the total pressure of the discharge fluid is delivered tothe reservoir through the inlet line. The low pressure probe includes anoutlet orifice facing downstream of the discharge fluid flow andcommunicates through the outlet line to the reservoir so that thereservoir also is exposed to the reverse dynamic pressure of thedischarge fluid. As a result, the anti-solidifying agent in thereservoir is driven from the reservoir through the outlet line and intothe flow of discharge gas by the driving pressure existing as thedifference between the total pressure and the reverse dynamic pressure.

Invention also resides in the provision of means for selectivelyadjusting the magnitude of the driving pressure to vary the amount ofsolidifying agent to be injected into the discharge fluid.

These and other objects and advantages of the present invention willbecome more apparent from the following description of the best mode ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a new and improved arrangement embodyingthe novel features of the present invention for injecting ananti-solidifying agent into the discharge piping from a safety reliefvalve in a pressurized system.

FIG. 2 is an enlarged cross-sectional view of a section of the dischargepiping where the anti-solidifying agent is injected into the flow pathof discharge fluid from the valve.

FIG. 3 is a cross-sectional view of the piping section taken along line3--3 of FIG. 2.

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in the drawings for purposes of illustration, the presentinvention is embodied in an arrangement 9 for injecting ananti-solidification agent 10 such as antifreeze from a reservoir 11 intothe piping 13 of a pressurized system 14 employing a safety relief valve15 (see FIG. 1). Herein, the valve includes a usual housing 16 shownmounted on a header 17 of a pressure vessel (not shown) with thedischarge piping 13 of the system connected to the housing around anoutlet 19. Within the valve, a valve closure member 20 is spring urgedinto a normally closed position covering a nozzle 21. When pressurewithin the vessel exceeds the set point of the valve the closure membershifts open for discharge gas to flow through the valve from thepressure vessel and into the discharge piping. To deliver theanti-solidification agent into the flow path of the discharged gas, aninjection line 23 communicates between an outlet 24 of the reservoir 11and the discharge piping so that as gas is discharged from the valve theanti-solidifying agent may be added to the gas stream.

In accordance with the primary aim of the present invention, a uniquearrangement is provided for using the energy of the discharging gasitself to inject enough anti-solidifying agent 10 to keep solids fromforming in discharge gases of the pressure relief system 14. For thispurpose, an inlet pressure line 25 communicates between the dischargegas flow path and the reservoir and is exposed to the total pressure ofthe discharge gas when flowing. The injection line 23 also communicateswith the discharge flow path but is exposed to the reverse dynamicpressure of the flowing discharge gas. In this way, anti-solidifyingagent inside of the reservoir is subjected to a high driving pressurederived from the difference between the total pressure of the flowingdischarge gas and its reverse dynamic pressure. Advantageously, withthis driving pressure, enough anti-solidifying agent can be injected inthe discharge gas to keep solids from forming even for the high massflows experienced by pressure relief systems for process gases withouthaving to rely on energy sources outside of the discharge gas.

More specifically, the inlet pressure line 25 communicates with thedischarge gas through a tubular probe 26 mounted within a bleed ring 27which defines a short section of the discharge piping 13 of the system.An upstream end 29 of the bleed ring is sealingly connected directly tothe valve housing 16 and similarly a downstream end 30 connects to theremaining section of the discharge piping. Extending through the wall 31of the bleed ring intermediate its ends are two probe ports 33 and 34.The two probe ports are located diametrically of each with the lowerport 33 as shown in FIG. 2 receiving the inlet probe 26. Connectedwithin the other port 34 is a second tubular probe 35 whose outer endportion 36 connects with the injection line 23 from the reservoir. Thetwo probes extend parallel with each other completely across the path ofdischarge gases within the bleed ring at an angle as is shown in FIG. 2with the inlet probe 26 inclined with respect to the central axis 37 ofthe ring at an acute angle upon progressing inwardly from the port 33.An inner end portion 39 of the inlet probe is seated within a recess 40located in the inner surface 41 of the wall 31 of the bleed ringupstream of the probe port 34. Similarly, the inward end 43 of thesecond or injection probe 35 is seated within a recess 44 locateddownstream of the probe port 33. By mounting the two probes in the bleedring in this way with the two probes also aligned longitudinally of thecentral axis 37 of the ring (see FIG. 3), a minimal resistance todischarge gas flow is achieved while also providing maximum materialthicknesses between the probe ports and ends of the bleed ring to helpinsure structural integrity of the ring when subjected to highpressures.

To supply high pressure from the discharge gas to the reservoir 11, theinlet or high pressure probe 26 includes a plurality (herein five areshown), of inlet orifices 45 formed through the side wall of the probe.The orifices are spaced equally from each other along the probe withinthe central portion of the flow path of the discharge gas. Specifically,the inlet orifices face directly upstream relative to the discharge gasflow from the valve. Thus, when oriented in this way, the pressure towhich the inside of the inlet probe and the anti-solidifying agent inthe reservoir 11 are exposed is the total pressure of the discharge gas.This pressure is of course significantly higher than the static pressureof the discharge gas.

Similarly, outlet orifices 46 in the injection probe 35 are spacedequally from each other along the probe within the central portion ofthe flow path of the discharge gas. In contrast to the inlet orifices,however, the outlet orifices face directly downstream relative to thedischarge gas flow so that the pressure to which the inside of theinjection probe and the reservoir outlet 24 are exposed is the reversedynamic pressure of the discharge gas. This latter pressure, of course,is significantly lower than the static pressure of the discharge gas.

With the outlet 24 of the reservoir 11 below the level of theanti-solidifying agent 10 (see FIG. 1), and with the reservoir otherwiseclosed except for the outlet being exposed to the reverse dynamicpressure and the interior of the reservoir exposed to the total pressureof the discharge gas, the resulting difference in pressure drives theanti-solidifying agent from the reservoir through the injection line 23and into the discharging gas from the relief valve 15. As theanti-solidifying agent is driven from the reservoir its volume isreplaced by discharge gas delivered to the reservoir through an inlet 47connecting with the inlet pressure line 25. When the valve closes, theflow of gas stops and so does the injected flow of anti-solidifyingagent because the two probes are then exposed to the same staticpressure and no driving pressure is created.

In accordance with another important feature of the present invention,the amount of anti-solidifying agent injected into the gas piping 13from the reservoir 11 may be adjusted selectively. For this purpose,adjustment means are provided for setting the driving pressure to belower than the pressure difference between the total pressure and thereverse dynamic pressure of the gas flowing through the piping. Byvirtue of this adjustment means, the concentration of theanti-solidifying agent in the gas can be set at a minimum for the gasflow condition of the pressurized system 14 which requires the greatestconcentration of agent to keep solids from forming.

In the exemplary pressure relief system 14, the greatest drop intemperature of the discharge gas occurs with the greatest drop indischarge gas pressure across the nozzle 21 of the valve 15. Using thevalve specifications and system conditions, ordinary engineeringtechniques may be employed to determine the mass flow of discharge gasat the greatest over pressure condition expected for normal operation ofthe valve and the concentration of anti-solidifying agent required tokeep solids from forming can then be determined. Flow ofanti-solidification agent from the reservoir 11 can be determinedempirically for different driving pressures. Also, the discharge gasflow at the greatest over flow condition can be simulated and applied tothe injection arrangement 9 to establish an actual maximum drivingpressure. Herein, adjustment of this driving pressure to some lowerdriving pressure is achieved by rotating the inlet probe 26 about itscentral axis so that the inlet orifices 45 face less directly upstreamthan for the maximum driving pressure. Thus, the pressure in interior ofthe inlet probe is reduced to a pressure less than the total pressure ofthe discharging gas. By selective rotation of the inlet probe betweenpositions with the inlet orifices facing directly upstream and facingdirectly perpendicular to the discharge gas flow, the pressure appliedto the interior inlet probe and through the inlet line 25 to thereservoir may be selectively varied between the total and staticpressures of the discharging gas to thereby selectively adjust flow ofthe anti-solidification agent from the reservoir.

To releasably secure the inlet probe 26 within the bleed ring 27, aconnector 48 includes an externally threaded body 49 secured within theprobe port 33. The inlet probe is telescoped through the body andextends into the ring. Integrally formed with and extending axiallyoutward from the body is a gripping member 50 having external threads 51and a tapered outer end portion 53. To lock the probe onto the body, aninternally threaded cap 54 is tightened onto the external threads 51 ofthe gripping member and a matching tapered section within the capengages the tapered portion 53 and wedges the gripping member againstthe probe locking the latter in the position selected. To reposition theprobe, the cap is threaded loose from its locked position for thegripping member to release the probe allowing it to be rotated into adifferent position.

As shown in FIG. 2, the injection probe 35 is mounted in the bleed ringin an identical fashion to the inlet probe mounting, wherein like partsof another connector 48 are identified by the same reference numbers. Itwill be appreciated that while adjustment in the driving pressure hasbeen described as being achieved by selectively positioning the inletprobe 26, driving pressure adjustment also may be accomplished byrepositioning the injection probe with the outlet orifices 46 orientedin position between facing directly downstream or directly perpendicularto the discharge gas flow. In this way, the pressure applied to theagent at the outlet orifices can be varied between the lowest possiblereverse dynamic pressure and the static pressure of the gas to vary thedriving pressure. Still other ways of varying the driving pressure arepossible such as by employing a variable flow restrictor in the inletline 25.

As another alternate feature of the present invention, the collection ofsolids on the high pressure probe 26 may be avoided by locating theinjection probe 35 upstream of the high pressure probe 26. In this way,anti-solidifying agent is discharged into the gas to lower thetemperature at which solids may form before the gas impinges the highpressure probe.

While the present invention has been described as incorporated in anarrangement 9 particularly suited to keep solids from forming in thedischarge gas of the pressure relief system 14 wherein the gas islimited to flowing in one direction, in an alternative version (notshown) wherein the gas may flow from either direction, the injection ofliquid from the reservoir 11 may be accomplished using either of the twoprobes as the liquid injecting probe. In this version, the probes arepositioned as described earlier relative to each other wherein theorifices of one probe face in a longitudinal direction opposite to thedirection which the orifices in the other probe face. However, in thereservoir, the ends of the lines connecting to the probes both terminatebelow the level of the liquid. As a result, depending upon the directionof gas flow, the probe with orifices facing downstream always will serveas the injection probe.

What is claimed is:
 1. A member flow-connectable with the piping of adischarge fluid flow system, said member comprising spaced apartupstream and downstream ends connected together by a generallycylindrical wall to define a flow path for fluid through said system,first and second probe ports substantially diametrically spaced fromeach other and extending through said wall, a first tubular probemounted within said first probe port and having an inner end portionextending substantially across said flow path in a non-perpendiculardirection relative to the central axis of said member, said inner endportion having a plurality of inlet orifices opening from one sidethereof and facing at least partially toward said upstream end of saidmember to communicate a high fluid flow pressure in said flow path tothe interior of said first probe, a second similar probe mounted withinsaid second probe port and having an inward end portion extendingsubstantially across said flow path in a non-perpendicular directionrelative to the central axis of said member, said inward end portionhaving a plurality of outlet orifices opening from one side thereof andfacing at least partially toward said downstream end of said member tocommunicate a low fluid flow pressure lower than said high fluid flowpressure in said flow path to the interior of said second probe, saidfirst and second probes having outer ends connectable to a source ofanti-solidifying fluid pressurizable by a driving pressure derived fromthe difference between said high and low pressures to drive saidanti-solidifying fluid from said source, through said second probe andinto the flow path of the discharge fluid flowing through said member,and connector means securing one of said probes to said member forselectively orienting the direction which the orifices of said one probeface between a first position facing in a generally longitudinaldirection relative to said flow path and a second position facing in agenerally perpendicular direction relative to said flow path to therebyselectively set said driving pressure at a value less than the maximumdischarge fluid flow pressure difference obtainable between said firstand second probes.
 2. A member flow connectable with the piping of afluid flow system, said member having spaced apart upstream anddownstream ends connected together by a wall to define a flow path forfluid in said system, first and second probe ports extending throughsaid wall, a first tubular probe mountable within one of said probeports with an inner end portion of said probe extending through saidwall and into said flow path, said inner end portion having at least oneinlet orifice opening through the side thereof with said first probeoriented to face said orifice to open at least partially toward saidupstream end of said member to communicate a high fluid flow pressure insaid flow path to the interior of said first probe, a second similartubular probe mountable within the other of said probe ports with anoutlet orifice opening from the side of the inner end portion thereofand at least partially facing toward said downstream end so as tocommunicate a fluid flow pressure lower than said high fluid flowpressure in said flow path to the interior of said second probe, andsaid first and second probes having outer ends connectable to a sourceof anti-solidifying fluid pressurizable by a driving pressure derivedfrom the fluid flow pressure difference between said probes to drivesaid anti-solidifying fluid from said source through said second probeand into the flow path of said fluid flowing through said system, andadjustment means for selectively setting said driving pressure at avalue less than the maximum fluid flow pressure difference obtainablebetween said first and second probes, said adjustment means including afirst releasable connector for securing one of said probes to said wall,said connector being movable between a locked position securing said oneprobe in a selected position against movement within said member and arelease position allowing said one probe to be moved within said memberto vary the angular orientation of said orifice of said one probeselectively between a first position facing in a longitudinal directionrelative to said flow path to and a second direction facingperpendicular relative to said flow path.
 3. A member flow connectablewith the piping of a fluid flow system, said member having spaced apartupstream and downstream ends connected together by a wall to define aflow path for fluid in said system, first and second probe portsextending through said wall, a first tubular probe mountable within oneof said probe ports with an inner end portion of said probe extendingthrough said wall and into said flow path, said inner end portion havingat least one inlet orifice opening through the side thereof with saidfirst probe oriented to face said orifice to open at least partiallytoward said upstream end of said member to communicate a high fluid flowpressure in said flow path to the interior of said first probe, a secondsimilar tubular probe mountable within the other of said probe portswith an outlet orifice opening from the side of the inner end portionthereof and at least partially facing toward said downstream end so asto communicate a fluid flow pressure lower than said high fluid flowpressure in said flow path to the interior of said second probe, andsaid first and second probes having outer ends connectable to a sourceof anti-solidifying fluid pressurizable by a driving pressure derivedfrom the fluid flow pressure difference between said probes to drivesaid anti-solidifying fluid from said source through said second probeand into the flow path of said fluid flowing through said system andsaid wall being generally cylindrical in shape and said first and secondprobe ports being formed through said wall substantially diametricallyopposite of each other.
 4. A member flow connectable with the piping ofa fluid flow system, said member having spaced apart upstream anddownstream ends connected together by a wall to define a flow path forfluid in said system, first and second probe ports extending throughsaid wall, a first tubular probe mountable within one of said probeports with an inner end portion of said probe extending through saidwall and into said flow path, said inner end portion having at least oneinlet orifice opening through the side thereof with said first probeoriented to face said orifice to open at least partially toward saidupstream end of said member to communicate a high fluid flow pressure insaid flow path to the interior of said first probe, a second similartubular probe mountable within the other of said probe ports with anoutlet orifice opening from the side of the inner end portion thereofand at least partially facing toward said downstream end so as tocommunicate a fluid flow pressure lower than said high fluid flowpressure in said flow path to the interior of said second probe, andsaid first and second probes having outer ends connectable to a sourceof anti-solidifying fluid pressurizable by a driving pressure derivedfrom the fluid flow pressure difference between said probes to drivesaid anti-solidifying fluid from said source through said second probeand into the flow path of said fluid flowing through said system andsaid flow path having a central longitudinal axis and said first andsecond probes extend into said flow path substantially parallel to eachother and in a non-perpendicular direction generally intersecting saidcentral longitudinal axis of said flow path.
 5. A member flowconnectable with the piping of a fluid flow system, said member havingspaced apart upstream and downstream ends connected together by a wallto define a flow path for fluid in said system, first and second probeports extending through said wall, a first tubular probe mountablewithin one of said probe ports with an inner end portion of said probeextending through said wall and into said flow path, said inner endportion having at least one inlet orifice opening through the sidethereof with said first probe oriented to face said orifice to open atleast partially toward said upstream end of said member to communicate ahigh fluid flow pressure in said flow path to the interior of said firstprobe, a second similar tubular probe mountable within the other of saidprobe ports with an outlet orifice opening from the side of the innerend portion thereof and at least partially facing toward said downstreamend so as to communicate a fluid flow pressure lower than said highfluid flow pressure in said flow path to the interior of said secondprobe, and said first and second probes having outer ends connectable toa source of anti-solidifying fluid pressurizable by a driving pressurederived from the fluid flow pressure difference between said probes todrive said anti-solidifying fluid from said source through said secondprobe and into the flow path of said fluid flowing through said systemand said wall including an inner surface and a recess formed in saidinner surface adjacent each of said probe ports, said first probe havingan inner end seated within said recess adjacent said second probe portand said second probe having an inner end seated within said recessadjacent said first probe port.
 6. A member flow connectable with thepiping of a fluid flow system, said member having spaced apart upstreamand downstream ends connected together by a wall to define a flow pathfor fluid in said system, first and second probe ports extending throughsaid wall, a first tubular probe mountable within one of said probeports with an inner end portion of said probe extending through saidwall and into said flow path, said inner end portion having at least oneinlet orifice opening through the side thereof with said first probeoriented to face said orifice to open at least partially toward saidupstream end of said member to communicate a high fluid flow pressure insaid flow path to the interior of said first probe, a second similartubular probe mountable within the other of said probe ports with anoutlet orifice opening from the side of the inner end portion thereofand at least partially facing toward said downstream end so as tocommunicate a fluid flow pressure lower than said high fluid flowpressure in said flow path to the interior of said second probe, andsaid first and second probes having outer ends connectable to a sourceof anti-solidifying fluid pressurizable by a driving pressure derivedfrom the fluid flow pressure difference between said probes to drivesaid anti-solidifying fluid from said source through said second probeand into the flow path of said fluid flowing through said system andeach of said probes including a plurality of said orifices axiallyspaced from each other along said probe, each of said orifices on saidprobe facing in the same direction.
 7. A member flow connectable withthe piping of a fluid flow system, said member having spaced apartupstream and downstream ends connected together by a wall to define aflow path for fluid in said system, first and second probe portsextending through said wall, a first tubular probe mountable within oneof said probe ports with an inner end portion of said probe extendingthrough said wall and into said flow path, said inner end portion havingat least one inlet orifice opening through the side thereof with saidfirst probe oriented to face said orifice to open at least partiallytoward said upstream end of said member to communicate a high fluid flowpressure in said flow path to the interior of said first probe, a secondsimilar tubular probe mountable within the other of said probe portswith an outlet orifice opening from the side of the inner end portionthereof and at least partially facing toward said downstream end so asto communicate a fluid flow pressure lower than said high fluid flowpressure in said flow path to the interior of said second probe, andsaid first and second probes having outer ends connectable to a sourceof anti-solidifying fluid pressurizable by a driving pressure derivedfrom the fluid flow pressure difference between said probes to drivesaid anti-solidifying fluid from said source through said second probeand into the flow path of said fluid flowing through said system andsaid inlet orifice being located in said flow path downstream of saidoutlet orifice.